Effect of betel nut chewing on the otolithic reflex system

Objective: This study investigated the effect of betel nut chewing on the otolithic reflex system. Methods: Seventeen healthy volunteers without any experience of chewing betel nut (fresh chewers) and 17 habitual chewers underwent vital sign measurements, ocular vestibular-evoked myogenic potential (oVEMP), and cervical VEMP (cVEMP) tests prior to the study. Each subject then chewed two pieces of betel nut for 2 min (dosing). The same paradigm was repeated immediately, 10 min, and 20 min after chewing. On a different day, 10 fresh chewers masticated chewing gum as control. Results: Fresh chewers exhibited significantly decreased response rates of oVEMP (53%) and cVEMP (71%) after dosing compared with those from the predosing period. These abnormal VEMPs returned to normal 20 min after dosing. In contrast, 100% response rates of oVEMP and cVEMP were observed before and after masticating chewing gum. In habitual chewers, the response rates of oVEMP and cVEMP were 32% and 29%, respectively, 20 min after dosing. Conclusion: Chewing betel nuts induced a transient loss of the otolithic reflexes in fresh chewers but may cause permanent loss in habitual chewers. Significance: Chewing betel nuts can cause a loss of otholitic reflex function. This creates a risk for disturbed balance and malfunction, for instance, during driving. (C) 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.